Abstract
Activities of the zinc ionic species in the 1-ethyl-3-methylimidazolium bromide (EMIB) -ZnBr2-ethylene glycol (EG) baths were calculated by the computer simulation method fitting the measured and calculated rest potential of Zn, and the relationships between the calculated activities and the results of the actual Zn electrodeposits were considered. Smooth and metallic colored Zn deposits with 100% of cathodic current efficiencies even at high current densities of 200-300 Am−2 were obtained from baths in which the activities of ZnBr42− were dominant compared with those of ZnBr3− and Br−. This suggests that ZnBr42− is the effective Zn ionic species for Zn electrodeposition. At compositions where the activities of ZnBr3− were relatively high, the dendritic deposits were obtained at the edge of the substrate. The reduction of ZnBr3− causes the dendritic deposits. The appropriate amount of EG addition to EMIB-ZnBr2 bath promotes the formation of ZnBr42− that forms the smooth Zn deposits.
